(1) Field of the Invention
The present invention relates to an electric conductor having an electrically conductive thin film, an actuator element using the electric conductor, and a method for producing the actuator. The actuator element of the invention is driven by an electrochemical process such as an electrochemical reaction, the charging and discharging of an electric double layer.
(2) Description of the Related Art
Patent Document 1 discloses an actuator element; the actuator comprises, as an active layer exhibiting conductivity and flexibility, a gel containing carbon nanotubes and an ionic liquid, and is capable of operating in air or in a vacuum.
Carbon nanotubes used as electric conductors are required to have excellent properties, such as high purity, high aspect ratio, high electric conductivity, and high specific surface area.
According to the known processes for producing actuator elements, it is difficult to uniformly mix polymer, ionic liquid, and carbon nanotube having the above excellent properties. As a result, the actuator obtained cannot exhibit desired high performance.
Known carbon nanotube have a length of about a few μm, making it difficult to form, using such type of carbon nanotube alone, a uniform electrode film that exhibits high electric conductivity. To alleviate the difficulty, a simple method of casting a mixture of carbon nanotube and a polymer binder makes it possible to easily obtain an electrically conductive thin film. The addition of a polymer, however, prevents uniform distribution of the carbon nanotubes in the film, and leads to lowered electronic and ionic conductions.    Patent Document 1: Japanese Unexamined Patent Application Publication No. 2005-176428